Microchip Technology MCP1642B-ADJI/MS

Overview

MCP1642B-ADJI/MS from Microchip Technology is a synchronous step-up DC-DC converter optimized for ultra-low-voltage battery-powered systems. It delivers up to 1A output at 5.0V from ≥3.6V input, starts reliably at 0.65V (typical), operates at fixed 1 MHz PWM frequency, and integrates true output disconnect shutdown with <1 µA quiescent current - enabling long-life operation in single-cell Li-Ion or alkaline portable medical sensors.

For engineers reviewing the MCP1642B-ADJI/MS datasheet, MCP1642B-ADJI/MS pinout, MCP1642B-ADJI/MS application, or MCP1642B-ADJI/MS equivalent, key selection criteria include verified low-startup-voltage capability (0.65V), confirmed 1.8A peak switch current limit, validated 1.21V feedback reference accuracy (±3%), and documented MSOP-8 package thermal resistance (211°C/W).

Technical Context

The MCP1642B-ADJI/MS implements peak-current-mode control with adaptive slope compensation, fixed 1 MHz switching, and integrated N-Channel (0.15 Ω R_DS(ON)) and P-Channel (0.3 Ω R_DS(ON)) synchronous switches. Its low-noise anti-ringing control suppresses high-frequency oscillations at the SW node during discontinuous conduction mode.

True output disconnect is enforced via gate control of the internal P-Channel MOSFET when EN is pulled low, eliminating DC path between VIN and VOUT while maintaining <1 µA shutdown current. The 1.21V feedback reference enables precise adjustable output (1.8–5.5V) using external resistor dividers, with IVFB ≤ 1.0 nA ensuring minimal divider current error.

Key Specifications

Pinout & Package

Package: 8-Lead MSOP (3.0 mm × 4.9 mm, 0.65 mm pitch), exposed pad not electrically connected - requires external PCB connection of EP to SGND/PGND for thermal performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous boost regulator applications.

Compared with TPS61200DRCT and MAX17222ETA+T, the MCP1642B-ADJI/MS uniquely combines sub-0.7V start-up, true integrated disconnect, and 1 µA shutdown in an MSOP-8 package - making it optimal for space-constrained, battery-critical medical and sensor designs where every microamp and millivolt matters.

Availability

MCP1642B-ADJI/MS is available at Aetrix Electronics and suitable for wireless sensor nodes, portable medical diagnostics, and PIC® MCU power management requiring stable component supply across industrial temperature range (-40°C to +85°C) and long-term production continuity.

Supply support for MCP1642B-ADJI/MS includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology is a U.S.-based semiconductor manufacturer specializing in microcontrollers, analog, interface, and power management ICs for embedded control applications.

The MCP1642B/D family was designed specifically for ultra-low-voltage battery-powered systems - targeting single-cell alkaline, Li-Ion, and NiMH/NiCd portable devices where start-up reliability and standby efficiency are critical.

FAQ

What is the minimum input voltage required for the MCP1642B-ADJI/MS to start regulating 3.3V output?

The MCP1642B-ADJI/MS starts regulating 3.3V output at 0.65V typical input voltage with a 1 mA resistive load. This value is confirmed in the Electrical Characteristics table under "Minimum Start-Up Voltage" and applies specifically to the MCP1642B-ADJ variant. Operation continues down to 0.35V after startup, enabling use with deeply discharged batteries.

Does the MCP1642B-ADJI/MS support adjustable output voltage, and how is it configured?

Yes, the MCP1642B-ADJI/MS supports adjustable output from 1.8V to 5.5V using an external resistor divider connected between VOUT, VFB, and GND. The internal 1.21V reference (VFB) sets the division ratio: VOUT = 1.21V × (1 + RTOP/RBOT). High-value resistors (e.g., 1 MΩ range) are recommended to minimize quiescent current and preserve light-load efficiency.

What does "True Output Disconnect" mean for the MCP1642B-ADJI/MS, and how is it activated?

"True Output Disconnect" means the MCP1642B-ADJI/MS completely isolates VOUT from VIN when disabled - turning off both internal switches and removing the body-diode path. It is activated by pulling EN low (<20% of VIN), resulting in <1 µA input current draw and zero DC output discharge. This feature is exclusive to the MCP1642B variant, not the MCP1642D.

What package type and thermal characteristics apply to the MCP1642B-ADJI/MS?

The MCP1642B-ADJI/MS uses an 8-Lead MSOP package (3.0 mm × 4.9 mm) with exposed thermal pad (EP). Its junction-to-ambient thermal resistance (θ_JA) is 211°C/W. The EP must be soldered to a thermally robust PCB copper area connected to SGND/PGND to achieve rated performance and prevent thermal shutdown under sustained 1A loads.

How does the Power Good (PG) pin function on the MCP1642B-ADJI/MS, and what external components are needed?

The PG pin on the MCP1642B-ADJI/MS is an open-drain output that pulls low when VOUT drops below 90% of its nominal value. It requires an external pull-up resistor (typically 10–100 kΩ) to VOUT or another logic rail. PG delay is 600 µs typical, with 3% hysteresis, enabling reliable MCU monitoring of output regulation status without additional supervision circuitry.